Comparison of prenatal smoking recorded on birth certificates with responses from the corresponding PRAMS surveys of new mothers in North Carolina

              State Center for Health Statistics Statistical Brief No. 32 – April 2007
N. C. Department of Health and Human Services 1 Division of Public Health
Comparison of Prenatal Smoking Recorded on Birth Certificates with
Responses from the Corresponding PRAMS Surveys of New Mothers in
North Carolina
by Paul Buescher and Fatma Simsek
Statistical Brief No. 32
North Carolina
Department of Health and Human Services
Division of Public Health
State Center for Health Statistics April 2007
Statistical
Brief
www. schs. state. nc. us/ SCHS/
Introduction
Birth certificates have been used extensively to
examine risk factors for low birth weight, preterm
birth, and infant mortality. Prenatal smoking has
been established as a key risk factor for these
adverse birth outcomes. 1,2 Birth certificate data have
also been used to target demographic groups and
geographic areas for prenatal smoking reduction
interventions. 3 A previous study in North Carolina
found that there was good agreement between
tobacco use during pregnancy on a sample of 1989
birth certificates and the corresponding medical
records. 4 Given the wide use of the prenatal smok-ing
data from birth certificates, we undertook this
study to further assess this smoking information.
Methods
The smoking information on birth certificates may
be collected in different ways, depending on the
practices of the hospital. Ideally, the prenatal
medical records would be consulted to gather this
information. Sometimes the mother is asked directly
whether she smoked during pregnancy and this
information is recorded on the birth certificate. The
birth certificate asks whether the mother smoked at
any time during pregnancy ( yes or no), and if yes,
how many cigarettes per day. Our evaluation of the
smoking information considers only the yes/ no
question and not the quantity of smoking.
The Pregnancy Risk Assessment Monitoring System
( PRAMS) is a survey of new mothers in North
Carolina. Sponsored by the Centers for Disease
Control and Prevention ( CDC), PRAMS is currently
conducted in 37 states, New York City, and the
Yankton Sioux Tribe in South Dakota. In North
Carolina, a random sample of live birth certificates
is selected on a monthly basis for PRAMS and these
mothers are contacted by mail, with telephone
follow- up for those who do not respond by mail.
The response rate for PRAMS is about 70 percent;
approximately 1,500 interviews are completed each
year. ( See www. schs. state. nc. us/ SCHS/ prams/ for
more information about North Carolina PRAMS.)
In the PRAMS survey, mothers are interviewed 3 to
5 months after the births of their babies and are
asked: “ In the last 3 months of your pregnancy, how
many cigarettes did you smoke on an average day?”
For this study, if the mother reported any response
other than “ none” she was considered to have
smoked during pregnancy. Note that the PRAMS
survey asks about smoking during the last three
months of pregnancy, whereas the birth certificate
asks about smoking at any time during pregnancy.
So the information from the two sources is not
exactly comparable.